As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
JUST PRIOR TO ENGINE START AN ACRID ELECTRICAL SMELL ENTERED CABIN AT THE TIME THE DUS WENT BLANK AND SEVERAL SYSTEMS FELL OFF LINE. FOUND P-91 WIRES TO BE BURNT. REMOVED AND REPLACED POWER DISTRIBUTION PANEL 91 PER M/M 24-21-21-4 OPERATIONAL CHECK OF SYSTEM OK.